What is colic? An evidence-based guide to excesssive infant crying

"Infantile colic" is the term that doctors use for excessive crying and fussing that has no obvious cause.

To make a diagnosis, many use the "rule of three," which identifies a baby as colicky if he or she is "otherwise healthy and well-fed," but has fits of "irritability, fussiness, or crying" that take up more than 3 hours of time each day for more than 3 days each week (Wessel 1954).

Caring for such an infant can be very stressful and frustrating, but doctors urge parents to remember: It's going to get better. The problem usually emerges around 2 weeks postpartum, and improves by 4-6 months.

Doctors also like to note that colic isn't usually associated with any serious, underlying medical problems.

The facts are reassuring, but they don't make colic go away, and it's vitally important not to trivialize the effects that colic can have on families.

In addition, colic can threaten a
parent's mental health, and harm family relationships. Parents are more likely to become depressed if their babies suffer from colic, and when parents are depressed, babies are at higher risk for developing insecure attachment relationships, perhaps because parents are struggling with feelings of helplessness, anger, or rejection (Pauli-Pott et al 2000).

So if
you're a parent struggling with a colicky baby, you deserve to be taken
seriously. And you should know you aren't alone.

Colic
is found in both breastfed and formula-fed infants. It's found among babies
born pre-term and babies born full-term. Exposure to tobacco smoke is a risk
factor, but colic is also common among the infants of nonsmokers.

But what's going on? Why are babies crying and fussing so much? What is colic from the standpoint of an infant's
physiology, health, and well being?

Let's
start by considering what a normal amount of crying and fussing looks like.

Understanding the developmental crying curve: What is normal, and what is colic?

All healthy, young babies cry and
fuss--sometimes inconsolably, and frequently without any obvious cause.
Typically, crying is more common in the late afternoon and evening.

It also seems that most healthy babies
cry according to a developmental schedule.

For example, when Dieter Wolke reviewed studies conducted in
Europe, North America, Australia, and Japan, he found that babies everywhere
tended to cry a lot during the first 6 weeks postpartum. At 5-6 weeks
postpartum, the average (mean) amount of crying was about 130 minutes a day.
But 25% of babies were crying for three hours a day or more.

By contrast, at 10-12 weeks, mean crying time had dropped to
below 70 minutes per day. Only 0.6% of infants this age were crying more than 3
hours a per day (Wolke et al 2017).

This, then, is the normal pattern for
infants in Western countries and Japan: Lots of crying at first, with a decline
after 6 weeks. Research suggests it's also the norm elsewhere, including some
hunter-gatherer societies (Barr et al 1991a).

So what is colic? Where should we draw the
line between normal and abnormal?

In earlier times, the word "colic" referred to pain in the area of the large intestine (the colon). Thus, identifying a baby as "colicky" meant you believed the baby was in pain, most likely because of an ailment of the gastro-intestinal tract.

Later, studies conducted in the 1950s cast doubt on the idea that babies who cried a great deal had intestinal difficulties. Researchers failed to find evidence that colicky babies had more gas, or higher rates of diarrhea and constipation (Illingworth 1954; Taylor 1957).

So many physicians and doctors started using the word "colic" in a new way -- one that made no reference to causation. In particular, they embraced the "rule of three," whicheliminates references to
abdominal pain, or indeed any sort of pain at all. Instead, it focuses on how much time babies spend crying and establishes a threshold for what's "too much."

If your baby cries a bit less than 3 hours a day, does that mean she's fundamentally different than one who cries for more than 3 hours a day? We have no reason to think so. The cut-off is arbitrary.

Moreover, in the real world, everyday judgments
about crying "too much" aren't just a function of time spent
crying, but also a function of the kind of care that a baby receives. We are more likely to consider a baby's cries "excessive" if his or her parents are attentive, sensitive, and responsive.

For this reason, I
think an important criterion for colic is that the colicky baby is much harder to
soothe.

Research supports this idea. Colicky
babies don't cry more frequently than other babies do. But
once they get started, they take longer to quiet down, and are more likely to
be inconsolable (Barr et al 1992; Barr 1998; Barr et al 2005).

What, then, causes colic?

There's no one answer to this question. As
typically defined, "colic" is a catch-all category for unexplained,
excessive crying. Different babies may be crying for different reasons.

Checking for signs of illness or pain

Despite appearing "otherwise healthy," some babies may be in physical pain, or suffering from an undetected ailment. So it's important to look for signs of illness.

Does your baby have diarrhea? Constipation? A urinary tract infection? These are common problems that you'll want to rule out.

Is it possible your baby is having an allergic reaction to something in his or her breast milk? Or formula? Is it possible your baby suffers from an intolerance to cow's milk protein, or a transient intolerance to lactose (Iacono et al 1991; Vanderplas et al 2015; Kanabar et al 2001)? Is your baby vomiting frequently -- perhaps because he suffers from gastroesophageal reflux disorder, or GERD (Vandenplas and Alarcon 2015)?

These aren't common problems, but a few babies do experience them, so they should be on your radar. It's also important to be on the lookout for symptoms consistent with an intestinal obstruction, or intussusception -- symptoms like a hard, distended abdomen, flexed legs, vomiting, or blood in the stool. It's rare, but very dangerous, so if you observe these signs you should consult your doctor right away.

The latest research also points to two other causes of colic: Infantile migraine, and an imbalance of bacteria types in the baby's large intestine.

It's not clear yet how common infantile migraine might be, in part because nobody is sure how to confirm that a baby is experiencing a migraine.

But studies show that babies with colic are more likely to have parents who suffer from migraines. They are also more likely to get diagnosed with migraines later in life. So there is good reason to suspect that at least some colicky babies are suffering from a condition related to migraine (Romanello et al 2013; Gelfand et al 2015; Qubty and Gelfand 2016; Sillanpää and Saarinen 2015).

As for the notion that colic is caused by an imbalance of bacteria in the gut, this could potentially explain a great many colic cases.

In theory, this could lead to low grade bowel inflammation, and also make babies more sensitive to pain in the gut. Adjusting a baby's gut flora -- so that a larger portion of the bacteria are the "good," probiotic type -- could prevent this from happening (Pärtty et al 2017).

In practice, several controlled studies show that colicky babies -- particularly those who are breastfed -- can experience improvements in their symptoms if they are given a treatment of probiotics. It doesn't always work, and some babies shouldn't try this therapy because they are immune-compromised.

For example, some babies may have highly reactive stress response systems. Their stress response systems go into overdrive in situations that don't ruffle a more mellow baby (Halpern and Coelo 2016).

Other babies may be experiencing a developmental lag in their ability to regulate emotions and bounce back from irritation (Barr 1998).

And researchers have proposed another, related idea: Maybe babies cry excessively because they haven't yet developed strong circadian rhythms of hormonal production. In the evening, they don't produce enough of the calming hormone, melatonin, so they're crankier at night. They don't sleep as well, either, which could make them more reactive and less able to self-regulate (Leuchter et al 2013).

In each of these scenarios, babies are easily triggered, and very slow to calm down. Parents can help them by tuning into what sets them off, and avoiding stimulation that stresses them out. For evidence-based tips, see this article about helping babies cope with stress.

This brings us to another type of answer to the "what is colic" question. Could colic be a response to the behavior of caregivers?

According to one idea, babies become colicky because their parents are anxious, depressed, or otherwise distressed (Halpern and Coelo 2016).

This isn't implausible, because stress is contagious. Experiments on year-old infants show that babies can sense and mirror the stress of their parents (Waters et al 2014; Waters et al 2017). Moreover, there is evidence suggesting that mothers are less likely to report colic in their infants if they have supportive partners (Alexander et al 2017).

But it's also obvious that colic causes stress in parents. Which comes first, the parental stress or the colic? Research hasn't settled the question.

Meanwhile, it's a sure bet that you should attend to your own stress levels and emotional needs.

And never handle a baby when you are feeling angry or near your breaking point. It's much better to leave your baby in her cot or crib than take any chances. If that means ignoring your baby's cries for a while, that's okay.

What about the other side of things? Problems that might arise because parents aren't responsive enough?

According to one theory, colic is caused by child-rearing practices that minimize responsiveness and physical contact between parents and babies. Thus, colic might be prevented if caregivers adopted a highly responsive, tactile approach to baby care--

holding or carrying the baby at least 80% of the time, and

giving the baby a breast or otherwise soothing him within seconds of hearing him cry.

But, as I explain elsewhere, this prediction hasn't been supported. Although the approach may reduce crying in normal, non-colicky babies (Hunziger
and Barr 1986), research has failed to show that it reduces crying
time in babies diagnosed with colic (Barr et al 1991b; St James-Roberts et al 1995; St James-Roberts et al 2006).

Perhaps
that's because the parents who volunteered for this study were the sort who had
already tried -- and failed -- to remedy colic by increasing responsive care.
Their babies belonged to the subset of colic sufferers who are inconsolable.

The bottom line?

I don't doubt that care-giving has crucial effects on babies, and it makes sense for parents to review their behavior if they've got a colicky infant. Seeking relief from stress and modeling calm is always a good idea. So is sensitive, responsive hands-on care. Tips like these can help you reduce your infant's stress levels.

But it's wrong to assume that babies have colic because their parents aren't being responsive, affectionate, or patient enough.